The present invention generally relates to the field of voltage regulation, and more particularly to a method and system for actively limiting transient voltages.
Modern high speed, high current drawing microcircuits such as processors, integrated memory circuits and peripheral interface circuits require a stable voltage for optimal performance. When multiple devices and circuits require a voltage supply, a bus is utilized which delivers a voltage generated by a conventional power supply. Microcircuits such as peripheral component interface (PCI) cards generate noise on the voltage bus. Power supplies are unable to react quickly enough to hold the voltage level of the bus within a desired range due to significant resistive and inductive parasitic elements between a power supply output capacitor and the microcircuits receiving an input voltage from the power supply.
In order to provide a stable voltage, the power noise sources may require isolation. Conventionally, buses have employed low equivalent series resistance (ESR) and low equivalent series inductance (ESL) capacitors near the control voltage inputs of the respective devices and circuits to attenuate voltage transients to an acceptable level. However, low ESR/ESL capacitors are passive elements that operate more slowly at limiting transients and limiting precision of a desirable voltage range. Low ESR/ESL capacitors must be placed close to the control voltage inputs of the microcircuits which causes additional design limitations. Additionally, low ESR/ESL capacitors are expensive and add significant cost to the voltage bus supplying microcircuits. Consequently, a method and system for actively limiting transients is necessary.
Accordingly, the present invention is directed to a method and system for actively limiting transient voltages across a voltage bus. In an embodiment of the invention, circuitry coupled to a bus may adjust a voltage level of a bus to a voltage within a desired range when transient voltages cause the voltage level on the bus to fall outside of a desired range. Circuitry of the present invention may include active elements that may adjust a voltage level of a bus in a rapid fashion to ensure devices coupled to the bus operate optimally while reducing the cost and design limitations of low ESR/ESL capacitors.